1. Field of the Invention
The invention relates to the field of forming Schottky barrier contacts to semiconductor materials.
2. Prior Art
A Schottky barrier contact has the advantage over a semiconductor junction diode that its forward voltage drop is controllable by the selection of the metal used in forming it. A Schottky barrier contact or diode is formed when an appropriate metal is deposited on a semiconductor material having a dopant concentration which is below a threshold concentration above which a desired Schottky barrier cannot be formed.
A dopant concentration which is higher than the threshold for Schottky barrier contact formation is often desirable in semiconductor devices, either at some portions of the wafer surface not within the Schottky barrier contact region or else within the portion of the wafer where the Schottky barrier contact is formed, but just far enough below the surface to allow the Schottky contact to be formed. In order to form a Schottky barrier contact at the surface of a semiconductor which has a dopant concentration which is higher than the threshold level, a low dopant concentration epitaxial layer is grown in order to support the Schottky contact.
An improved technique is needed for forming Schottky barrier contacts to the surface of semiconductor layers which have high dopant concentrations.